Sherlock Holmes is asked by Jack Bennett to investigate after his fiancée Edith Presbury sees the shadow of a man in her window in the middle of the night. The problem is that her bedroom is on the second floor and there is no way for any man to have been able to get to that window. Edith is the daughter of a notable natural scientist, Professor Presbury, a widower who is engaged to be married to a much younger woman, Alice Morphy. The Professor is quite displeased at hearing that Bennett, who also happens to be his assistant, has hired the Great Detective and Holmes and Watson are unceremoniously escorted off the property.When Holmes reads of a rash of thefts from zoos - all monkeys and apes - he slowly begins to unravel the mystery of the shadow Miss Presbury saw in her window. Written by
Did You Know?
: Being the last episode of the series to be involved with as producer, he performs a cameo as zoo cleaner in the background of the zoo scene where Lestrade talks to the zoo director. His face is barely recognizable, but this event is mentioned in "A Study in Celluloid: A Producer's Account of Jeremy Brett as Sherlock Holms" by Michael Cox, 1999, Rupert Books Cambridge. See more
Near the end, Holmes gives Lestrade the Professor's syringe case. As Holmes picks up the case, a newspaper is revealed underneath with the headline "SCOTLAND YARD SOLVES MONKEY MYSTERY". The text below the headline, however, has nothing at all to do with the case. See more
You may inform the Secretary of the Royal Society that I have entitled my Michaelmas lecture 'Darwin's Fundamental Error'.
That'll raise a few hackles, sir.
Will it not.